Automatic telephone system



Jill 29 1924; 1,502,877

A. J. RAY

AUTOMATIC TELEPHONE SYSTEM Filed Feb 23. 1921 4 Sheets-Sheet 1 53 W in15 34/ Inuan mr.

July 29. 1924.

A. J. RAY

AUTOMATIC TELEPHONE SYSTEM I Filed Feb. 23'.

1921 4 Shg ts-Sheet 2 fi'zuenlmr 'Hf'fhur JHE July 29 192$.

7 AV .1. RAY

AUTOMATIC TELEPHONE SYSTEM 4 Sheets- Sheet 5 Filed Feb. 23. 192] Imafi1:1r

July 29 1924. 1,502,877

A. J. RAY I AUTOMAT I C TELEPHONE SYSTEM Filed Feb. 23, 1921 4Sheets-Sheet 4 Patented July 29, 1924.

UNITED TEES PATENT OFFICE.

ARTHUR- J. BAY, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRICCOM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed February 23, 1921. Serial No. 447,011.

To all whom it may concern:

Be it known that I, ARTHUR J. RAY, a citizen of the UnitedStates ofAmerica, and a resident of Chicago, Cook County, and State of Illinois,have invented certain new and useful Improvements in Automatic TelephoneSystems, of which the following is a specification.

My invention relates in general to an improved automatic telephonesystem, and more specifically to improved apparatus for use in a systemwhere multiparty lines are employed and where the lines are providedwith repeating coils individual thereto. In such a system, it will beseen that it is necessary to disconnect the repeating coil from a linewhen a call is extended thereto and to provide a direct path forgenerator cur rent to the bells of the called line.

Among the objects of my invention are, therefore, to'provide improvedcircuits and devices for accomplishing the above result without the useof complicated mechanism such as has been used in the past, and toprovide certain details and minor features of improvement in connectionwith the above features which will be pointed out more clearly in thefollowing specification.

I have chosen to illustrate my invention in connection with a multipartyline system of one specific type, but it should be under stood that thefeatures of this invention may be applied as well to any well known type,of party or straight line telephone system in which it may be desiredto disconnect certain apparatus such as a repeating coil from a linewhen connection is made therewith.

In the drawings I have shown, in Figures 1, 2, 3, and 4, sufficient ofthe circuit diagrams and apparatus to fully illustrate my invention.

Fig. 1 shows a selector-repeater B which is individual to a line havingconnected thereto substations A and A. It will be understood thatalthough only two substations are shown there may be 10 or 12 on a lineeach having its individual code signal which will later be described.The selector repeater B is of well known type but modified to illustratethe features of my invention.

Fig. 2 shows a connector which is of the well known Strowger type beingmodified to operate in conjunction with code selecting and ringingequipment shown in Fig. 3.

Fig. 3 shows a code selecting switch F, a code interrupter I, and a coderinging swltoh K Fig. 4 shows my invention applied to a simple repeaterD on the called line, which repeater is controlled over a simplexcircuit. This repeater is individual to the called subscribers line andbetween the line and its line switch C. The line switch C is of a wellknown rotary type although the Keith type might be used. The subscribersstations are of the same type as shown in Fig. 1 having the magneto forcalling parties on their own line.

I will now point out the features of my invention by describing theoperation of the system when a call is extended from one line toanother. Let us assume that a subscriber at substation A (Fig.' 1)wishes to communicate with asubscriber at substation E (Fig. 4). Thesubscriber at A would remove his receiver thereby allowing hisreceiver-hook to assume an intermediate or listening position in contactwith only spring 62, whereupon the subscriber would listen in toascertain the condition of the line. Should he hear conversation on theline he will hang up the receiver without interfering with theconversation of the other party on the line. Should he have removed thereceiver during a period between codes of a call being extended on hisline, he would hear an audible signal or occupancy tone and would knowthat a call was already being eXtended-on his line, whereupon he wouldhang up his receiver. Now should he remove his receiver and find theline idle he would operate the arm N to allow the receiver hook to alsoengage with springs 21 and to cut in the talking circuit, and

extend ground over both sides of the line to the line relay of theselector repeaterB, over a simplex circuit. traced as follows: ground,springs 85 of the calling device (CD), springs 21, windings of theringer magnets 22 in parallel over both sides ofthe line, break springsof relay 2, windings 3 and 5 of the induction coil, conductor 54,winding of relay 6, to grounded battery. Relay 6 will energize over thiscircuit, thereby closing a circuit for relay 10, traced from ground,springs 26 and 24, springs 31 of relay 4, windingof relay 10 to battery.Relay 6 also closes one point in a bridge of the talking circuit atsprings 7 8 and 29 which will later be extended to the line relay 100 ofconnector H (Fig. 2). Relay 10 in operating closes a point in thevertical magnet circuit at springs 61 and extends ground to the privatenormal conductor 80 at working cont-act of springs 86 to make the linebusy to other lines.

Assuming-that the substation wanted is number 12345. The subscriber willnow operate his calling device to send out the desired numbers ofimpulses, thereby opening the circuit of the relay 6 at springs 85 thedesired number of times. Each time relay (3 falls back a circuit iscompleted for relay 12 and vertical magnet 16 in parallel to step theswitch to a desired level. Relay 12 is slow acting and therefore remainsenergized during the series of impulses. Relay 14 also energizedimmediately after the energization of relay 12 over a circuit tracedfrom battery, winding of 14, oif normal springs 36 (the off normalsprings having closed after the first vertical step) break springs 37 ofrelay 8, springs 33 and 32 of relay 12, and springs 35 of relay 10 toground. A locking circuit for relay 14 isnow completed which may betraced from battery through winding of said relay, otl' normal springs36, springs 38 of magnet 18, springs 46 of relay 14, and springs 53 ofrelay 8 to ground. Upon cessation of the series of impulses the relay 12will fall back and in so doing will close a circuit for the: rotarymagnet 18 which may be traced as follows: grounded battery, winding ofmagnet 18, make contacts 39 of relay 14, break springs 32 and 34 ofrelay 12, make springs 35 of relay 10 to ground. This circuit for therotary magnet 18 is broken as soon as relay 14 falls back, the relay 14having its locking circuit opened at springs 38 upon the operation ofmagnet 18, although springs 38 will again close springs 46 will remainopen. The single rotary impulse of magnet 18 caused the wipers 41, 40and 42 to be brought in contact with the first of a group of trunksleading to a group of connectorssimilar to the connector H, shown inFig. 2. .If the first trunk is busy there will be ground present on thprivate wiper 40 which will furnish a new circuit for relay 14,-tracedfrom battery, winding of relay 1.4, off normal springs 36, break springs38 of magnet 18, springs 43 and 44 of relay 8, wiper 40 to the busy orgrounded trunk. It will be seen that each time relay 14 energizes acircuit will be again completed for magnet 18 as before, each time thatmagnet 18 is energized the circuit of 14 will be broken at springs 38 ofmagnet 18. This action will continue until an idle trunk is found afterwhich relay 1'4 willremain deenergized and the rotary motion of magnet18 will be dis continued.

lVhen such idle trunk is reached relay 8 -144-146, inclusive.

which has previously been short circuited by ground on busy trunks,energizes over a circuit traced from battery, winding of relay 14, oftnormal springs 36, springs 38 of magnet 18, cam springs 47, (cam springsare operated on eleventh rotary movement only) winding of relay 8,springs 35 of relay 10 to ground. Relay 8 is of higher resistance thanrelay 14 and therefore relay 14 does not energize at this time. Relay 8in energizing operates to complete a circuit for relay 100 of connectorswitch H (Fig. 2) over a circuit traced from battery, upper winding ofsaid relay, upper break contacts of relay 100, conductor 58, contact 49,wiper 41, springs 48, 29 and 78, windings 7 and 0 of the repeating coil,conductor 52, wiper 42, contact 55, conductor 69, lower break springs ofrelay 109, lower winding of relay 100 to ground.

The calling subscriber may now operate his calling device in accordancewith the second digit of the desired number, and in so doing will againopen the circuit of relay 6 the predetermined number of times. Relay 6while operating maintains the relay 12 in operated position closingsprings 51 to provide a direct bridge across the talking circuit,shunting the windings 7 and 9 of the repeating coil. Each time relay 6deenergizes, the circuit of relay 100, which may now be traced throughthe direct bridge including the springs 51 of relay 12, is opened atsprings 7 8 and 29.

At each interruption at the springs 78 and 29 the line relay 100 fallsback and operates the vertical magnet 102 in series with relay 103,raising the switch shaft and wipers to the second level. Slow actingrelay 103 is accordingly energized, and, in conjunction with theswitching of the vertical otl' normal springs on the first verticalstep, shifts the path of the impulses from the armature 151 of the linerelay 100 so that they come through armature 124 and its workingcontact. lVhen the slow acting relay 103 deenergizes after the series ofvertical impulses the impulsing circuit is shifted from the verticalmagnet 102 to the rotary magnet 110.

In response to the calling of the third digit 3 of the called number,the rotary magnet 110 rotates the wipers 141-143, in elusive, intoengagement with contacts Slow acting relay 114 is energized in multiplewith the rotary magnet and remains energized during the entireoperation. The operation now de pends upon whether the called line isbusy or idle. If it is busy ground is present on test contact 145 andbusy test relay 118 energizes over the following circuit: from groundedcontact 145 through wiper 142, armature 115 and its working contact,armature 134 and its resting contact, and relay 118 to battery. When theslow acting relay 114 falls back, said relay 118 remains locked up overa circuit that includes its armature 130. The test relay 118 also opensthe rotary magnet circuit at armature 111 in order 'to prevent furtherrotation of the wipers in case the calling dial is again manipulated,and at armature 119 completes a connection from the busy signallingmachine to-the lower line conductor. This operation gives the callingsubscriber an audible busy signal to inform him that the called line isbusy, and he will hear the signal and replace his receiver.

Let us assume, however, that the called line is idle when the connectorH is operated, as before explained, to establish connection therewith.Under these circumstances as soon as the slow acting relay 114deenergizes upon the cessation of the rotary movement, the followingcircuit is completed: from ground through the working contact ofarmature 120 and said armature, armature 130 and its resting contact,upper winding of relay 117, resting contact of armature 115 and the saidarmature, test wiper 142, test contact 145, switching relay 271 of thecalled line switch C and through the stepping magnet 273 to battery.Relays 117 and 271 e11- ergize over the above traced circuit. Relay 271,upon enrgizing, removes the line relay bridge at the line switch C,while relay 117 locks itself to ground, completes at armatures 133 and137 the connectionto the line wipers 141 and 143, and closes a circuitfor relay 116 which operates to shift the operating circuit to conductor176 leading to the code selector F.

In response to the fourth digit 4 of the called number the verticalmagnet 201 of the code selector F receives four impulses over operatingconductor 176. The first impulse comes through vertical off normalsprings 211 and 209, slow acting relay 202 and vertical magnet 201 tobattery. Upon the first vertical step the 0H normal springs operate andrelay 202 energizes and completes a new path for the impulses asfollows: from conductor 176 through off normal springs 211 and 210,armature 238 and its working contact, relay 202, and vertical magnet 201to battery. The vertical magnet and the slow relay 202 receive threemore impulses over the new circuit which stepsthe switch shaft andwipers up until they stand opposite the fourth level of bank contacts.Soon after thelast vertical impulse the slow acting relay 202deenergizes and when it does so it switches the impulsing circuit to therotary magnet 203 over the following path: armature 238 and its restingcontact, armature 227 and its resting contact, slow acting relay 204 andthrough rotary magnet 203 to battery.

The calling subscriber may now operate his calling device in accordancewith the last digit 50f the desired number. A series of impulses, asbefore, come over the operating circuit. In response to these impulsesthe rotary magnet operates to step the wipers 234 and 235 intoengagement with the fifth set of contacts in the fourth level, oppositewhich they were previously raised. Relay 204 is energized in series withthe rotary magnet 203 and at armature 225 closes a circuit for relay 205which energizes and locks itself to conductor 173 and thence through theresting contact of armature 128 and said armature, armature 123 and itsworking contact to ground. At armature 227 relay 205 opens the circuitfor the rotary magnet; however, relay 204 at armature 224 previouslyclosed a multiple circuit so that the rotary magnet circuit is heldclosed until the end of the last impulse when it is opened by thefalling back of relay 204, which prevents further rotation of the wipersin case the calling subscriber should again operate his calling device.Relay 205, upon energizing, also closes at armature 223 a circuit forthe interrupter I. Relays 261, 262, and 263 receive a momentary impulse.Relays 263, 262, and 261 open the circuits of relays 262, 261, and 263,respectively. Relay 261, being of the ordinary quick acting type, fallsback first and closes again the circuit for relay 263. Relay 263 remainsenergized for a time and holds the circuit to relay 262 open. Relay 262,upon deenergizing, closes again the circuit for relay 261 which operatesand breaks the circuit for relay 263 which, upon deenergizing, closesagain the circuit for relay 262. This operation continues until groundis removed from conductor 239 and, as relays 262 and 263 are both slowto fall back, the relay 261 is e11 ergized and dcenergized at intervals,thus sending out interrupted ground at armatures 212, 219, and 220.

Relay 204, upon deenergizing after the last rotary impulse, completesthe following circuit: from interrupted ground, conductor 213, throughthe resting contact of armature 221 and said armature, working contactof armature 222 and said armature, and stepping magnet 214 of codesending switch K. As soon as ground issent over this circuit thestepping magnet 214 energizes and when the ground is removed magnet 214deenergizes. Stepping magnet 214, upon deenergizing, advances the switchwipers 236 and 237 into engagement with the first set of contacts 227and 228 of their associated banks. Vipers 236 and 237, upon. reachingcontacts 227 and 228, complete the following circuit: from groundedcontact 228 through wiper 237 conductor 206, wiper 236, conductor 240,relay 231, and resistance R to battery. Relay 231 energizes over theabove traced circuit and locks itself to ground over ground conductor173. Relay fifth contact set current flows from- 231 upon energizingcompletes the following circuit for the slow relay 286 of the repeaterD, to provide a direct, circuit for ringing current to the called line,ground spring 233, conductor 17 5, upper winding of 'ring-cut-ott' relay125, spring 126 and its back contact, springs 133, wiper 1 11, contact 111 conductor 117, springs 284C and 285 and relay 286 to battery. Relay125 does not energize over this circuit due to the high resistance ofrelay 28b. Relay 286 upon energizing disconnects the windings 279 and280 from the called line and closes a circuit including springs 288 and289 and their front contacts including the condenser 290 thus preventingthe ringing current from passing through the repeating coils. hen groundcomes again over conductor 213 it operates stepping magnet 211 over itspreviously traced circuit and also operates ringing relay 217 over thefollowing circuit: from ground over previously traced circuit toarmature 222 and thence t-hrough the resting contact of armature 215 andsaid armature, armature 216 and its working contact, and relay 217 tobattery. When relay 217 operates, its armature 218 shifts conductor 174from ground at the signalling device Y to ground through generator G.Ringing currentfrom generator G flows over conductor 174, through theresting contact of armature 129 and said armature, armature 137 and itsworking contact, wiper 1&3, contactv 14:6, line conductor 148, spring288 and its front contact through the stations E-E etc. in multiple, andback through spring 289 and its front contact, condenser 290, over lineconductor 147, contact 1 14:, wiper 14t1, working contact of armature133 and said armature, armature 126 and its resting contact, upperwinding of ring cut-off relay 125, conductor 175 and armature 233 andits working contact to ground. All the bells on party line X areoperated but relay 125 is not operated, due to its design andadjustment. Vhen ground is removed from conductor 213, relay 217deenergizes and shifts conductor 17 1 back to ground through deviceY'and the stepping magnet 211 deenergizes to step the wipers onto thesecond set of contacts. hen ground is again placed on conductor 213relay 217 operates to connect generator on the called line and thestepping magnet attracts its armature and when the ground is removedfrom conductor 213 relay 217 shifts its armature from generator toground and the magnet 211 releases its armature to step the wipers 236ant. 237 onto the third set of bank con- 'tacts. This process continuesuntil the bells on party line X have been rung four times and the magnet214 has been deenergized to step the wipers from the fourth to the fifthset of contacts. hen the wipers reach the grounded conductor 206 throughwiper 236, the fifth contact in the bank of said wiper, conductor 265,contact 243 in the fifth set on the fourth level of the bank of codeselector F, wiper 23 1, and relay 232 to battery. Relay 232 energizesover this circuit and at armature 215 opens the circuit to ringing relay217. Vhen ground is again placed upon conductor 213 stepping magnet 21 1operates as before but obviously relay 217 cannot operate, as itscircuit is open at armature 215 and therefore, the bells on party line Xare not rung. However, when stepping magnet 21s: deenergizes and stepsthe wipers 236 and 237 into engagement with the sixth set of contactsrelay 232 falls back and reestablishes the circuit for relay 217. W henground is again. placed upon conductor 213 the bells on the called lineare rung as before. The effect of energizing relay 232 is to cause atime interval of break to occur in the regular periodical rings sent outto the called line so as to distinguish between the first digit of thecode and the second. Now it will be seen that the bells on party line Xhave been rung four times and after a short interval they have startedringing again. As pointed out, the bells are rung while the wipers areon the sixth set of contacts and they will continue to ring each timethe interrupter I places ground on conduct-or 213 until the eleventhcontact set is reached, when the bells will have been rung live moretimes thus completing the code call l-5. When the wipers are steppedonto the eleventh contact set current flows from grounded conductor 206through wiper 236 and the eleventh contact in its associated bank,conductor 2G6, contact 2 1% in the bank of the code selector F, wiperand resistance R to battery. This circuit shunts the relay 231 andallows it to fall back and when it does so it opens its locking circuit,opens the circuit of ringing relay 217, and at arn'iature places batteryon conductor 175 through resistance R. It will be seen that when relayfell back the circuit of the slow relay 286 of repeater D was opened atspring and said relay will deenergize after an interval and restore theconnections of the repeating coil windings 279 and 280 to the calledline. Also when relay 217 deene'rgizcs, ground is fed to the called linethrough a winding of an induction coil in the device Y to place asignificant tone on the called line. This is done to indicate to anysubscriber who may listen in at this time that a call is in progress andthe line in use. This occupancy tone is placed on the called linethrough the windings Y278 and 277 of the repeater D and throughcondenser 282. Relays 281 and 286 being both deenergized at this time.Vhen the stepping magnet energizes and deener-- gizes again the wipers236 and 237 are advanced to the twelfth contact but the bells on theparty line X are not rung because the circuit for ringing relay 217 isopen and it cannot, therefore, place generator on the line. In case thecalled subscriber does not respond immediately, the code sending switchK continues to rotate step by step and repeats the code as it passesover the remainder of the contacts, because the first contact ismultiplied with the thirteenth, the second with the fourteenth, etc. Theswitch K will continue to rotate step by step and the proper code willcontinue to be sent out on the party line X until the called subscriberanswers.

If the called subscriber answers at the end of the code the relay 231will at that time be in deenergized condition and the.

following circuit for the relay 281 will be closed at springs 291 of thecalled line, ground through the calling device, springs 291, the coilsof the ringer in parallel, two sides of the line and windings 279and-280 in parallel and through relay 281 to battery. Relay 281 uponenergizing closes the following circuit for the ring cut-off relay 125.From ground through resting contact of armature 218 of relay 217, ofswitch F, conductor 174,- springs 129, springs 137, wiper 143, contact146, repeating coil windings 278 and 277, springs 283 and 284, conductor147, contact 1 1 1, wiper 141,.springs 133, springs 126, relay 125,conductor 175, springs 233 and its resting contact to battery throughresistance R. Relay 125 energizes over the above traced direct currentcircuit, locks itself at armature 127 to grounded conductor 177, extendsthe called line to the back bridge relay 109, and at armature 128 itdisconnects conductor 173 from grounded conductor 173.

As soon as the wipers 236 and 237 are stepped onto either the twelfth orthe twenty-fifth contact set in their associated banks, no ground willbe present on conductor 206, for the energization of relay 125 removedground from conductor 173.

Relay 205 accordingly deenergizes, removes ground from startingconductor 239, opens the interrupter ground at armature 222fin case theinterrupter I should be operating due to some other call, and closes atarmature 226 and its resting contact a point in the release circuit.

Returning now to the. connector, when the called line is extended to theback bridge relay 109 the talking circuit is completed. Relay 109 isenergized while the receiver at E remains off the hook and reverses thedirection of current flowing in the dialing loop of selector repeater B.This operation is of no utility in the present disclosure, buton'account of its being a standard operation the circuits are shown inthis Way.

I Conversation may now take place over the established connection andwhen it is finished both subscribers replace their receivers. Therelease of the equipment is brought about by the replacement of thereceiver at the calling substation A which opens the circuit for theline relay 6 at springs 21. Relay 6 upon deenergizing opens the circuitof relay 10 and closes one point at springs 26 and 27 in the circuit ofrelease magnet 20 which circuit is completed when relay 10 falls backand closes'spring 61 with its back contact. Release magnet 20 energizesand restores the selector repeater B to normal. Relay 6 upondeenergiz'ing also opens the circuit of relay 100 of the connector H atsprings 78 and '29. The falling back of relay 100' is followed by thedeenergization of release relay 101 which removes ground from therelease circuit for connector H andcode selector F The deenergization ofthese relays completes a circuit for the release magnet 190 ofconnectorH and for release magnet 221 of the selector F. This circuitmay be traced from ground through armature 151 and its resting contact,armature 122 and its resting contact, conductor 171, resting contact ofarmature 226 and. said armature, conductor 172, and in multiple through011 normal springs 208 and 207 and release magnet 221 of code selector Fto battery, and off normal springs 107 and 108 and release magnet 190 ofconnector H to battery. The release magnets 190 and 221 energize overtheabove traced circuit and restore their respective switches to normal.

It could be shown how any one of a plurality of combinations is sentout, but it is thought that with the explanation already given, anexamination of the drawing (Fig. 3) will clearly show how many codes maybe sent out on any party line that appears in the banks of connector H.

As previously pointed out, during the time that the relay 231 of codeselector-F is energized, the return path of the generator is connectedto ground at armature 233. Ring cut-off relay 125 of the connector H,included in the circuit of relay 286 and' for ringing current, canenergize only when direct current of a definite value flows through it,and since relay 231 does not deenergize until the end of the code,suflicient direct current cannot flow through the circuit due to thehigh assistance of relay 286, and the ring-cut-oif relay cannot energizeto break the ringing current. As before pointed out, the deenergizationof relay 231 ends the last digit of the code and upon deenergizing, itconnects battery at armature 233 through resistance R to the circuit, sothat should the called subscriber have hisreceiver off the hook or if heremoves it before relay 231 energizes again to repeat the code, directcurrent flows over the circuit previously traced for relay 125, whichenergizes and completes the talking circuit in a manner alreadyexplained. The code ringing switch K, however, does not stop as soon asthe called party answers but continues to advance step by step until thewipers reach one of their normal positions. Should the called partyanswer before the end of his code, all the bells on the line willcontinue to ring until the code is completed, due to condenser 290preventing them from being shunted at the called station. Upon the codebeing completed relay 2S6 falls back to extend the talking circuit tothe called stationand to allow the energization of relay 281 to completethe previously traced energizing circuit of the ring-cut-ott relay 125.

It the called subscriber does not respond, the calling subscriber willhang up and he is likely to do so while the code is being sentout. Itthe code should be stopped immediately when the calling subscriber hangsup, many times the last code would be that of some other subscriber andnot the one that is wanted. In the present disclosure, however, the codewill be completed even though the calling subscriber does hang up hisreceiver before its completion. Upon referring to the drawings, it willbe seen that neither the connector H nor the code selector F can releaseand that code sending switch K cannot stop until relay 205 of se lectorF deenergizes. Now when the calling subscriber hangs up and allowsrelays 100 and 101 to deenergize ground is removed from conductor 173 atarmature 123, but ground is kept on conductor 1'73 from wiper 237, overconductor 206, working contact of armature 228 and said armature. Thisground holds relays 117, and 205 energized until the wipers of switch Kreach the twelfth. or twenty-fifth contact set. IVhen they do so thecode has been finished, ground is no longer present on them, relays 117and 205 deenergize, and switches F and 11 release in the usual manner.

It should be understood that, although the calling line here shown isequipped with a selector repeater individual thereto and the called linehas a repeater and a line switch individual to it, any line may beequipped with either type of circuit desired and will operate in themanner contemplated by my invention, that is, the repeater D is in allrespects similar to the corresponding parts of the selector repeater Bexcept in one case a line switchis directly controlled by the repeater,while in the other case a selector is directly controlled by therepeater. I will now describe in general the operations ensuing when acall is made to a line such asthat having sta tions A, A, etc., merelyto show the similarity of the two repeaters.

In case a call is made from any other line in the system to the line Athen a connector, similar to H will make contact with normals 79, 80 and81 or line A in the same manner that connection was extended to thenormals 144:, 145 and 14-6 of the line X, ex cept of course that thecode selecting mechanism would be operated in accordance with the codeof the line A. In this case, relay 2 of the selector repeater B will beoperated when the relay 231 of the code selector F energizes. Relay 2operates to close the springs 13 and 15 and springs 23 and 82, therebydisconnecting the repeating coil windings 3 and 5 from the called lineand providing a direct path for signalling current from normal conductor79, through condenser 83, springs 15 and 13 through the ringers of thestations in parallel and back over the other side of the line throughsprings 23 and 82 and to the other normal conductor 81.

It will thus be seen that I have provided a very simple arrangement forcutting off the repeating coil from a line when connection is madethereto, without the use of tuned relays or other complicated mechanism,and for providing a direct path for ringing current to the bells of thatline with no shunting paths to weaken the strength of the ringingcurrent.

Having fully described and ascertained the featuresand aspects of myinvention, what I consider to be new and desire to have protected byLetters Patent will be pointed out in the appended claims.

lVhat I claim as my invention is:

1. In a telephone system, a line, a connector switch having access tosaid line, means for operating said connector to extend a connection tosaid line, a relay in said connector and a relay individual to saidline, said individual relay energized in series with said other relay bydirect current, means in said connector for supplying ringing current tosaid line through the winding of said relay in the connector, andcontacts on said individual relay for closing the ring ing circuit.

2. In a telephone system, a line, a connector switch having access tosaid line, a relay in said connector, another relay, a winding of saidfirst relay acting as a conductor for ringing current supplied to saidline by said connector, and at the same time acting as a conductor foroperating said other relay, contacts on said other relay for extending aringing circuit to said line, and a third relay operative when thecalled subscriber answers to permit the operation of said first relay.

3. In a telephone system, a called subduring the ringing perlod.

4. In a telephone system, a line, a repeat ing coil having windingsnormally in bridge of said line, a connector for seizing said line, aring cut ofl relay in said connector, a second relay connected in serieswith said cut oil relay when the line is seized and adapted whenoperated to cut off said repeating coil and to complete a ringingcircuit to the called line, and means operative when the calledsubscriber responds for cutting off said second relay and for completingan operative circuit for said first relay.

5. In a telephone system, a line, a repeater individual to said line, aconnector for seizing said line, means associated with said connectorfor applying ringing current to the line when called, a pair of relaysassociated with said repeater, a ring cut off relay included in theringing circuit, means for rendering one relay of said pair responsiveto the seizure of the line to disconnect said repeating coil and tocomplete the ringing circuit, and the other relay operative on theresponse of the called subscriber to complete an operating circuit forsaid cut oil' relay.

In witness whereof, I hereunto subscribe my name this 9th day ofFebruary, A. D., 1921.

ARTHUR J. RAY.

